CVE-2022-21656: envoyproxy envoy Improper Certificate Validation

Vulnerability summary

CVE-2022-21656 is a high (CVSS 7.4) Improper Certificate Validation vulnerability in envoyproxy envoy. EPSS estimates a 0.67% chance of exploitation in the next 30 days, higher than 51.2% of scored vulnerabilities.

Timeline

1. 22-02-2022
   PublishedVulnerability first disclosed.
2. 23-04-2025
   Last modifiedVulnerability information updated.

Description

Envoy is an open source edge and service proxy, designed for cloud-native applications. The default_validator.cc implementation used to implement the default certificate validation routines has a "type confusion" bug when processing subjectAltNames. This processing allows, for example, an rfc822Name or uniformResourceIndicator to be authenticated as a domain name. This confusion allows for the bypassing of nameConstraints, as processed by the underlying OpenSSL/BoringSSL implementation, exposing the possibility of impersonation of arbitrary servers. As a result Envoy will trust upstream certificates that should not be trusted.

• CWE-295Improper Certificate ValidationThe product does not validate, or incorrectly validates, a certificate.
• CWE-843Access of Resource Using Incompatible Type ('Type Confusion')The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.